tests: add a maxrss for compiling std lib C backend .c file

I observed clang taking 8G to compile the output from the std lib tests
using the C backend. This commit should make the Windows CI stop failing
due to OOM.

test/tests.zig

@@ -1017,6 +1017,7 @@ pub fn addModuleTests(b: *std.Build, options: ModuleTestOptions) *Step {
                 .name = qualified_name,
                 .link_libc = test_target.link_libc,
                 .target = altered_target,
+                .max_rss = if (mem.eql(u8, options.name, "std")) 9126805504 else 0,
             });
             compile_c.overrideZigLibDir("lib");
             compile_c.addCSourceFileSource(.{